Electronic timing system for sorting apparatus



Oct. 30, 1945. c. E. SMITH 8 ELECTRQNIC TIMING SYSTEM FOR SORTING APPARATUS' 7 Filed July 29, 1941 4 2 Sheets-Sheet 1 INVENTOR WITNESSES:

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Oct. 30, 194 5. c, sMlTH 7 2,387,952

I ELECTRONIC TIMING SYSTEM FOR SORTING APPARATUS Filed July 29, 1941 2 Sheets-Sheet 2 INVENTOR l I ATTORNEY\ Patented Oct. 30, 1945 mac'rnomo'rnvmm SYSTEM FOR son'rnvo arrana'rus Clyde a. Smith, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, 1'a'.,.a corporation of Pennsylvania Application July 29, 1941, Serial No. 404,527

11 Claims.

This invention relates to an electronic timing system, and has particular relation to apparatus for designating heterogeneous portions of moving material. 7

In certain industrieasuch as the canning industry, steel is supplied from the rolling mills in the form of a long continuous strip of sheet material. The strip is then fed to a shearing mechanism which cuts it into sections. Before reaching the shearing mechanism, the sheet material is passed through an inspecting device arranged to detect any pinholes which are present therein. On the opposite side of the shearing mechansim from the inspecting device is a diverting gate which is positioned adjacent the path of the movng sections of sheet material. The diverting gate is normally inoperative, permitting the sections of material to pass from the shearing mechanism to a storage bin or other apparatus, if desired. However, upon the detection of a pinhole, the inspecting device initiates operation of apparatus which causes the gate to be interposed in the path of the moving sections of material. After the gate has separated the section containing the pinhole, it is returned to its inoperative position.

The speed 01 the moving material varies over a wide range. It may be as low as 100 feet per minute or as high as 1000 feet per minute. Since the inspecting device and diverting gate are spaced irom each other, the operation of the latter should occur a predetermined time after the detection of a pinhole, the length of the time interval being dependent upon the speed of the material. In apparatus constructed in accordance with the teachings of the prior art, considerable difliculty is encountered in obtaining precise and uniform timing of the operation of the gate. With irregular timing, the apparatus is sometimes arranged to separate a number of sectionsupon the detection of a single pinhole to insure separation or the heterogeneous section. The resulting waste of material is obviously undesirable.

Ittis accordingly an object of my invention to provide apparatus for accurately and consistently operating mechanism for designating heterogeneous portions of moving material.

Another object of my invention is to provide a novel apparatus for operating mechanism for designating heterogeneous portions or moving material in which the operation is timed with respect to the speed of the material.

An additional object or my invention is'to provide apparatus ioroperating mechanism for terval'being dependent upon the speed of the' material. 4

A general object of my invention is to provide apparatus for effecting operation of a load device in which the operation is timed with respect to l the magnitude of a physical quantity.

An ancillary object of my invention is to provide a novel electrical circuit for timing the operation of a, load device..

Another object of my invention is to provide apparatus for classifying and sorting moving material whose speed is variable in which the time a of operation of a sorting device following inspection 01 the material varies inversely as the speed of the material. a

Still another object of my invention is to provide apparatus for use in classifying and sorting moving material having different speeds which operates a sorting device when material or one classification has moved a predetermined distance from a classifying device regardless oi the speed of the material.

A more specific object of my invention is to provide apparatus for sorting heterogeneous portions of moving material which includes means for properly operating a diverting gate at one location along the path 01' the material in response to the detection of a heterogeneity at another location.

In accordance with "my invention as applied to the sorting or heterogeneous portions of moving material, I provide a charge-storing means, such as a capacitor, arranged to be supplied! with charging current through an electric discharge device. The discharge device has a constantcurrent voltage characteristic over a substantial range of potential and the flow of current therethrough is initiated upon the detection of a heterogeneity. The rate of flow or the charging current is controlled in accordance with the speed of the moving'material. Consequently, the rate of charging of the storing means is dependent upon the speed or the material.

An electric discharge valve oi the arc-like type is interposed between a source of direct-current potential andthe operating means for the diverting gate. When the charge on the storing means attains a predetermined value, the valve is rendered conductive. A capacitor is also connected to the valve and when the latter is rendered conduotive, charging of the capacitor begins at the terial.

' panying drawings.

same instant that the operating means is energized. An auxiliary circuit is provided which in- .cludes means responsive to the charge on the time of energization of the operating means for the gate is dependent upon the time required to charge the storing means to the predetermined value. The charging time of the storage means in turn is dependent upon the speed of the ma- The period during which the operating means remains energized is constant regardless of the speed of the material, and'is determined by the rate of charging of the capacitor. It is to be noted that oncethe leading edge of a section of the sheet material is diverted by the gate, that section is separatedfrom the others even if the gate operating means is deenergized before the entire section passes the gate. The constants of the circuit for charging the capacitor are so set that the operating means remains energized for a period sufflcient to separate the heterogeneous section at the slowest speed of the material. With precise and uniform timing of the operation of the gate, a constant period of energizetion of the operating means is permissible without an excessive loss of material.

The novel features that I consider character istic of my invention are set forth with particu- 1 larity in the claims. The invention itself, however, both as to its organization and its method v of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment when read in connection with the accom- In these drawings,

Figures 1a and 1b taken together form a diagrammatic view showing a preferred embodiment of my invention.

In the apparatus shown in the drawings, a strip of sheet material 3 is fed through rollers 5 past an inspecting device I to a shearing mechanism 9. The shearing mechanism cuts th material into sections which pass over a conveying system comprising a plurality of conveyors I l and I3. A diverting gate I5 is located between the conveyors H and I3 and is normally in the position shown in full lines. Upon the detection of a pinhole by the inspecting device I, the diverting gate I5 is raised to a position as shown by the dotted lines. The heterogeneous section is then diverted into a discard bin l1. After the separation of the heterogeneous section, the diverting gate is returned to its original position, permitting the material to pass from one conveyor to the other.

photoelectric tube or a number of photoelectric tubes connected in parallel. When a pinhole is present in the material, energy passes from the source through the hole to the photosensitive device 21, and the latter causes an impulse to be transmitted to an amplifying system indicated generall at 29. The output of the amplifying system is impressed through leads 3| and 33 between the grid 35 and cathode 31 of a thyratron tube 39 forming part of a control unit 4 I.

The control unit 4| includes a second thyratron tube 43, a pair of current relays 45 and 41, and a source of direct-current potential 49. The control circuit of the second thyratron 43 may be traced from the grid 5| through a grid resistor 53, lead 55, a capacitor 51, a second resistor 59 and lead 53 'to the cathode 6| of the tube. The

x end of resistor 59 which is connected to the oathode 6| is also connected through resistor 65 to the positive terminal of the source 49, and the other end is connected through leads B1 and 69 to the negative terminal of the source. As long as relay 41 is deenergized, the capacitor 51 remains uncharged because of a shunt circuit extending from one plate of the capacitor through lead 61, resistor H and contactor 13 of the relay 4! to the other plate. Thus, a negative grid-cathode potential exists in thyratron 43. A capacitor 14 is connected between-the grid and cathode to cooperate with the other constants of the circuit in determining the grid-cathode potential at which thyratron 43 fires.

A detailed explanation of the amplifying system illustrated is not necessary to a complete understandingof my invention. It is suiiicient that lead 3| is normally positive with respect to lead 33. 4

When the impulse initiated by the photosensitive device 21 passes through the amplifying syse tem 29, lead 33 becomes positive with respect to lead 3|, causing thyratron 39 to be rendered conductive. Current then flows in a circuit extending from the positive terminal of the source 49 through lead I5 normally closed contactor 11' of the relay 45, the coil '19 of the control relay 41 to the anode 8| of the thyratron 39. The circuit then continues from the cathode 31 of the thyra- The speed of the material 3 is governed by the speed of the shearing mechanism 9. The means for driving the shearing mechanism is indicated symbolically bya motor l9 supplied from a source 2| of alternating-current potential. /A generator 23 is also connected to the shearing mechanism,

and the magnitude of the voltage generated thereby varies in accordance with the speed of the material.

The inspecting device 1 comprises a source of radiant energy 25 and a photosensitive device 21 positioned on opposite sides of the material 3.

' The photosensitive device may take the form 01 a the source 49. The control relay 41 is thus ener gized to open its contactor 13 in the circuit shunting the capacitor 51'. The capacitor 51 is then charged through a circuit extending from the positive terminal of source 49, lead [5, variable resistor 83, resistor 95, lead 55, capacitor 51 and leads 5! and 59 to the negative terminal of the source. After a predetermined interval of time, the capacitor 51 is charged sufllciently to make the grid 5| positive with respect to cathode 6| and the second thyratron 43 is rendered conductive.

The thyratron 43 is connected in a circuit receiving potential from the alternating-current source 2| through an auxiliary transformer 81. The circuit extends from one terminal of the secondary .89 of'the transformer 81 through the coil 9| of the relay 45 to the anode 93 of the thyratron complete deenergization thereof when thyratron 39 becomes non-conductive. It is then apparent terminal oi the voltage divider III through the contactor .II to the anode III 01' an electric dis-.

charge device III. p The circuit continues from a cathode III of the device III through a variable ;.resistor III and a capacitor III to the negative assassin 1' the control thyr'atron. The-source of biasing'potential III maintains a negative grid-cathode terminal of the voltage divider m and a bleed resistor III is connected across the resistor Ill and capacitor III. i

The electric discharge device III is of the type through which the current flow is independent of the anodeacathode potential. For this device a pentode,xdesignated commercially as a RCA-I8 tube, is preferred. While the current flow through the pentode III is independent of the anode-cathode voltage, it is dependent upon the potential impressed between one 01' its grids III and the cathode I I I. Over a portion of the char-- operated. The potential of the generator II is I impressed through a pair of leads III and III between the grid III and cathode III of the pentode. A grid resistor IIIis connected between the grid III and lead III and resistor III ties the grid III to cathode III. Thus, the flow of current through the pentode is dependent upon the speed of the moving material. It is evident that the capacitor III in circuit with the pentode will be charged at a rate which is also dependent upon the speed of the material.

The capacitor III is included in the control circuit of another thyratron tube III. This thyratron is preferably a Westinghous KIT-627 tube. The control circuit extends from the grid III of the thyratron III through a grid resistor III and the capacitor III to the negative terminal of the voltage divider III. The control circuit continues from an intermediate tan III on the divider III through a variable resistor III and I the primary III or an impulse transformer III to the cathode III of the thyratron III. The

potential until current flows through the primary III of the impulse transformer. At that time, the potential of the secondary III causes the grid III to become positive with respect to the cathode III and renders the control thyratron III conductive. The control thyratron is preferably 9. Westinghouse ICU-676 tube and is interposed between a source of direct-current potential III and the solenoid III for raising the diverting gate II. The source of direct-current potential III may be taken from the rectifier III. However, it is illustrated as an independent source because such is probably preferable in view of the load to be placed thereon. A voltage divider III is connected across the source oi potential III. when the control thyratron III is rendered conductive, current flows from the positive terminal oi the divider III through a parallel circuit comprising the lower portion III of a variable resistor III and a capacitor III on one side and the upper portion III of the variable resistor III on the other side; and continues through the anode III and cathodeI II of the control thyratron I", lead "I, the coil III of the solenoid III and lead "I to the negative terminal of the divider III. A variable resistor Ill and a capacitor I'IIin series with each other are also connected between the cathode III of the control thyratronIII and the negative terminal of the divider III. It is apparent that, when the control thyratron I" becomes conductive, the current flows simultaneously through the energizing coil III of the solenoid III and the capacitor III. Thus, the capacitor III is charged at a. constant rate from the instant the diverting gate II is raised. Ableed resistor III is connected across the resistor I" and capacitor III.

The capacitor "9 in circuit with the control thyratron II! is also included in the control circuit'oi' another thyratron III, which may be called a stop tube and is preferably a Westinghouse KU-IZ'! tube. The control circuit of the stop tube III extends from the grid III thereof through grid resistor III, the capacitor III to v.th'e negative terminal of the voltage divider III,

portion of the voltage divider III in the control circuit causes a negative potential to be impressed between the grid III and cathode III of' the thyratron III. However, when the charge on the capacitor m in circuit with the pentode m attains a predetermined value, it counteracts the I negative biasing potential and causes the thyra- --tron III to become conductive. Current then flows from the positive terminal of the voltage divider III through the contactor II of the relay grid resistor III,-the secondary III and a source or biasing potential III to the cathode III of and from an intermediate tap III of the divider through-a resistor III, a contactor III and energizing coil III of an auxiliary relay III to the cathode III. The portion of the voltage divider in the control circuit 01' the stop tube III establishes a negative grid-cathode potential preventin the tube from becoming conductive. How-' ever, when the charge on the capacitor III in circuit with the control thyratron III attains a preselected value, it impresses a positive potential between the grid III and cathode III of the stop,

tube III, rendering it conductive. Current then flows from the positive terminal of divider III through resistor III, stop tube III, coil III, contactor III, resistor III to the intermediate tap III of the divider.

While current is flowing through the control thyratron III, the capacitor III connected across the variable resistor III is charged with its nesative plate connected to the anode III of the control thy'ratron III. The positive plate of the capacitor III is connected to the anode III of v the stop tube III. When the stop tube becomes conductive, the capacitor III is connected across the anode III and cathode III of the control thyratron I" through the stop tube III, the portionof the voltage divider between the intermediate tap III andvthe negative terminal and When the control relay 41 is deenergized in the manner previously described, one of its con- .on said storing means attains a preselected magtactors 93 opens the anode circuit of the pentode HI, stopping the charging of the capacitor H9 in circuit therewith. 'At the same time another contactor IOI of the relay 41 closes to effect discharge or the capacitor I I3 through a resistor "I connected in parallel therewith. Deenergization of relay 41 also causes contactor I03 of the relay to close to effect discharge of the capacitor I1! in circuit with the control thyratron'I41 through a resistor 203 in parallel therewith.

The operation of the apparatus commences when energy from the radiant source 25 passes through a pinhole to the photosensitive device 21. An impulse is then transmitted through the amplifying system 29 to the control unit 4I,

causingthe control relay 41 to be energized.

Upon energization of the control relay 41, charging of the capacitor I I9 in circuit with the pentode is initiated. The capacitor H9 is charged at a rate dependent upon the speed of the moving material 3, and when the charge attains a predetermined value, the control thyratron I41 is rendered conductive as a result of the flow of current through the impulse transformer I39.

The coil I13 of the solenoid I51 is energized when the control thyratron is rendered conductive and raises the diverting gate I5. At the same instant that the gate is raised, current flowing through the control thyratron begins to charge capacitor I19. After a predetermined period of v time, the capacitor I19 in circuit with the control thyratron I41 attains a charge sufilcient to render the stop tube I8I conductive. The stop tube I8I then permits the charged capacitor I63 to extinguish the control thyratron I41 and shortly thereafter the auxiliary relay I95 breaks the cathode circuit of the stop tube I8I. When the control thyratron I41 is extinguished, the coil I13 of solenoid I51 is deenergized to permit the diverting gate I5 to return to its original position.

Although I have shown and described a certain specific embodiment of my invention, I am fully aware that many modifications thereof are possible. My invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and by the spirit of the appended claims.

I claim as my invention:

1. A control circuit for operating mechanism for designating heterogeneous portions of moving material comprising, charge-storing means, means connected to said storing means for charging said storing means at a rate dependent upon conductive.

of energy from said supply means to said actuating means and said capacitor when the charge nitude, and means connected to said supply means and responsive to a charge 01' a predetermined magnitude on said capacitor for interrupting the supply of energy to said actuating means.

2. A control circuit for operating a mechanism for designating heterogeneous portions of moving material comprising, charge-storing means, means connected to said storing means for charging said storing means at a rate dependent upon the speed of said material, means connected to said charging'means and responsive to a heterogeneity in said material to initiate charging of said storing means by said charging means, actuating means for said designating mechanism, an electric discharge valve of the arc-like type in circuit with said actuating means, means connected to said valve and actuating 'means for supplying energizingcurrent to said actuating means under the control of said valve, control means connected to said valve and responsive to the charge on said storing means for rendering said valve conductive when said charge attains a preselected magnitude, and timing means connected to said valve for interrupting the conductivity of said valve a predetermined time after it is rendered 3. A control circuit for operating a mechanism for designating heterogeneous portions of moving material comprising, charge-storing means, means connected to said storing means for charging said storing means at a rate dependent upon the speed of said material, means connected to said charging means and responsive to a heterogeneity in said material to initiate charging of said storing,

means by said charging means, actuating means for said designating mechanism, a capacitor, an

electric discharge valve of the arc-like type in circuit with said actuating means and said capacitor, means in circuit with said valve, actuating means and capacitor for supplying energy through said valve to energize said actuating means and charge said capacitor, control means connected to said valve and responsive to the charge on said storing means for rendering said valve conductive when the charge attains a preselected magnitude, and timing means connected to said valve and responsive to a charge of a preselected value on said capacitor for interrupting the conductivity of said valve.

' 4, A control circuit for operating a mechanism for designating heterogeneous portions of moving material comprising, charge-storing means, means connected to said storing means for charging said storing means at a rate dependent upon the speed or said material, means connected to said charging means and responsive to a heterogeneity in said material to initiate charging of said storing means by said charging means, actuatin means the speed of said material, means connected to for said designating mechanism, a capacitor, an electric discharge valve of the arc-like type in circuit with said actuating means and said capacitor, means connected to said valve for sup-1 plying energy through said valve to energize said actuating means and charge said capacitor, means connected to said valve and responsive to the charge on said storing means for rendering said valve conductive when the charge attains a preselected magnitude, timing means including a second electric dischargevalve connected in circuit with said first valve for interrupting the conductivity of the latter, and control means connected to said second valve and responsive I assassa to a charge of a preselected value on .said'cative.

5. A control circuit for operating mechanism for designating heterogeneous portions or moving material comprising, an electric discharge device having a plurality of principal electrodes. and

.pacito'r for rendering said second valve conducbeing of the tim through which the currentflow is substantially independent of the potential across said principal electrodes, said device having a control. electrode whereby the current flow may be varied, means adapted to iunction as a to said control electrodes for varying the flow of,

current through said device in accordance with the speed oi saidmaterial, actuating means for said designating mechanism, an electric discharge valve of the arc-like type in circuit with said actuating means, means in circuit with said valve and actuating means for supplying energizing current to said actuating means under the control of said valve, and control means connected .to said valve and responsive to the charge on .material comprising, an electric discharge device having a plurality of principal electrodes and being or the type through which the current flow is substantially independent of the potential across said principal electrodes, said device'having a control electrode whereby the current flow may be varied, means adapted to function as a source of direct-current potential, charge-storing means, circuit-means connecting said storing means in circuit with said source through said principal electrodes including switch means for completing said connection in response to a ,responsive to a capacitor potential of a prem: selected value ior interrupting the conductivity said connection in response to a heterogeneity I in said materiahmeansconnected to said control b electrodes for varying the flow of current through said device in accordance with the speed or said material, actuating means for said designating mechanism, a capacitor, an electric discharge valve of the arc-like typein circuit with said actuating means and said capacitor, means'connected to said valve for supplying energy through said valve to energize said actuating means and charge said capacitor, means connected to said valve and responsive to the charge on said storing means for rendering said valve conductive when the charge attains a preselected magnitude, and timing means connected to said valve and of said valve.

8. A timing system comprising means adapted to function as a source of direct-current potential, a; pair of capacitors and a load device in circuit with said source, an electric discharge valve of the arc-like type interposed in circuit with said source, load device and capacitors to control the flow of current from said source to energize said load and charge said capacitors, means connected to said valve to render it conductive, normally non-conductive m'eans connecting one or said capacitors in a second circuit with said valve in which the potential of said one capacitor when charged is suillcient to render said valve non-conductive upon said non-conductive means becoming conductive, and means connected to said other capacitor and said normally non-conductive means to render the latter conductive when said other capacitor is charged to a preselected potential.

9. A timing system comprising means adapted to function as asource oi direct-current potential, a pair of capacitors and a load device in circuit with said source, an electric discharge valve of the arc-like type interposed in circuit heterogeneity in said material, means connected to said control electrodes for varying the flow of current through said device in accordance with the speed of said material, actuating means for said designating mechanism, an electric discharge valve of the arc-like type in circuit with said actuating means, means in circuit with said valve and actuating means for supplying energizing current to said actuating means under the control of said valve, control, means connected to said valve and responsive to the charge on said storing means for rendering said valve conductive when said charge attains a preselected magnitude, and timing means connected to said N valve for interrupting the conductivity of said valve a predetermined time after it is rendered conductive.

I. A control circuit for operating mechanism -!or designating heterogeneous portions of moving material comprising, an electric discharge device having a plurality oiprincipal electrodes and being or the type in which the current flow is substantially independent or the potential across said principal electrodes, said device having a control electrode whereby the current flow may be varied, means adapted to function as a source oi direct-current potential, charge-storing means,

circuit means'connecting said storing means in circuit with said source through said principal electrodes including switch means for completing with said source, load device and capacitors to control the flow 01' current from said source to energize said load and charge said capacitors, means connected to said valve to render it conductive, circuit means including a second electric discharge valve of the arc-like type connecting one or said capacitors in a second circuit with said valve in which the potential of said one capacitor when charged is suflicie'nt to render said valve non-conductive upon said second valve becoming conductive, and means connected to the other capacitor and said second valve to render the latter conductive when said other capacitor is charged to a preselected potential.

10. A control circuit for operating a mechanism for designating heterogeneous portions of moving material comprising, charge-storing means, means connected to said storing means for charging said storing means at a rate dependent upon the speed of said material, means connected to said charging means and responsive to a heterogeneity in said material to initiate charging oi. said storing means by said charging means, actuating means for said designating mechanism, a pair of capacitors, means adapted to function as a actuating means to control the flow of current i from said source to energize said actuating means and charge said capacitors, means connected to said valveto render it conductive. normally nonconductive. means connecting one of said capaci-to'rs in a second circuit with said valve in which the potential of said one capacitor when charged is sumcient to render said valve non-conductive upon said non-conductive means becoming conductive, and .means connected to said other capacitor and said normally non-conductive means to render the lattenconductive when said other capacitor is charged to a preselected potential.

11. Atiming system comprising a pair oi electric discharge valves otthe arc-like type, each having an anode, cathode and control electrode, a first resistor connected in 4 circuit from the anode of one valve to the anode of the other valve, 9, first capacitor connected in parallel with said first resistor, means adapted to function as a source of direct-current potential having a positive terminal connected to an intermediate point on said first resistor and a negative terminal, first circuit means including a second variable resistor and a second capacitor connected from the cathode of said one valve to said negative terminal, means connected to said control electrode and cathode of said one valve to render it conductive whereby current flows from said source through said one valve to charge said first and second capacitors, second circuit means connecting the control electrode of said other valve to a point in the circuit between the oathode oi said one valve and said second capacitor.

and third circuit means connecting the cathode of said other valve to a point in the circuit between said second capacitor and the positive terminal of said source. CLYDE E. SMITH, 

